1. Field of Endeavor
Exemplary embodiments of the present disclosure relate to a method for measuring opening and closing delay time of elevator brake, and more particularly to a method for measuring opening and closing delay time of elevator brake configured to prevent a roll-back phenomenon of an elevator by automatically calculating elevator brake opening/closing delay time for setting elevator brake opening/closing time, and to allow a stable performance of brake operation.
2. Discussion of the Related Art
Elevators installed inside and/or outside of a building for lifting persons or cargos are mostly of hoist winding type or rope type elevators using friction of wire ropes. The rope type elevator rotates a hoist using rotation force of a motor, where a wire rope contacting the hoist is operated and moved by rotation of the hoist. At this time, torque generated from the motor increases or decreases in response to situations such as persons inside the elevator box, cargo weight or vertical operational directions.
A load imbalance between an elevator car and a balance (counter) weight is continuously generated in the rope type elevator due to loaded weight of persons and cargos in an elevator car, and a heavier force is applied to a direction on a contact surface between a hoist and a wire rope as much as the imbalance, thereby resulting in a moment to be applied to a shaft of the hoist.
A drum type brake applied to an elevator is configured such that a spring is connected to a brake arm, and a brake shoe attached to the brake arm is brought into contact with a brake drum to generate a brake torque, where the brake arm is connected to a brake plunger. The brake shoe is contacted to the brake drum in an elevator to prevent a motor from rotating at a stationary state and a force pressed by the brake shoe to the brake drum is expressed as a compression force of spring.
When a signal is transmitted to a brake driving unit from a controller of an inverter or from an elevator control panel in order to operate an elevator, an electricity is supplied to a brake plunger after a predetermined delayed time, whereby the brake plunger open a brake arm attached to a brake lining to start the operation of the elevator.
Meantime, an elevator brake opening/closing time is an important element for determining a motor control time, and a time delayed until a brake is mechanically opened and closed was arbitrarily set by a user. At this time, the time of the brake being opened and closed is set to be a bit delayed over a time of controlling a motor, where a roll-back phenomenon of an elevator being instantly leaned to a weightier side between an elevator car and a balance weight may be generated, when a brake delay opening and closing time is set at an excessively smaller value. Conversely, although the roll-back phenomenon of the elevator may be prevented when a brake delay opening and closing time is set at an excessively greater value, wear of brake lining disadvantageously increases because the brake shoe is opened after the motor starts to rotate in a state of the brake shoe holding the brake drum.